Treatment of ores and precipitation of precious metals from their cyanid solutions.



ENITED STATES ATENT l Fries.

FREDERICK WILLIAM MARTINO AND FREDERIG STUBBS, OF SHEFFIELD,

ENGLAND.

TREATMENT OF ORES AND PRECIPITATION OF PRECIOUS METALS FROM THEIR CYANID SOLUTIONS.

SPECIFICATION forming part of Letters Patent No. 651,510, dated June 12, 1900. Application filed March 20, 1899. Serial No. 709,834. (No specimens.)

.To all whom it may concern:

Be it known that we, FREDERICK WILLIAM MARTINO, residing at Sharrow, Sheffield, and FREDERIO STUBBS, residing at Sheflield, England, subjects of the Queen of England, have invented certain new and useful Improvements in or Relating to the Treatment of Ores and the Precipitation of Precious Metals from Their Oyanid Solutions, (for which we have made application for Letters Patent in Great Britain under No. 4,925, dated the 6th day of March, 1899,) of which the following is a specification.

This invention relates to the precipitation of precious metals from their cyanid solutions, its primary object being to obviate the necessity for the use of zinc in such processes.

The present invention is a development of that forming the subject of our previous application for United States Letters Patent, Serial No. 700,107, filed December 23, 1898. In the specification accompanying that application we described the use of calcium carbid and acetylene; but We have now found that similar reactions take place when instead of calcium carbid any metallic carbid which produces a hydrocarbon gas when brought into contact with Water is used. We have also found that all the hydrocarbon gases which can be so produced react in a substantially similar way to acetylene and, moreover, that this reaction occurs however such hydrocarbon gases are manufactured. As an example, aluminium carbid, which o n being treated with Water produces methane, may be mentioned.

It is to be clearly understood that in this specification wherever the terms metallic carbid or hydrocarbon gas are mentioned they are to be read as indicating, respectively, any metallic carbid or hydrocarbon gas of the kinds above referred to.

i The hydrocarbon gas is passed through a cyanid solution containing the precious metal-say goldora metallic carbid may be added to the liquid, thus producing a nascent hydrocarbon gas. In either case the gold is precipitated.

When a hydrocarbon gas is passed through the cyanid solution, its action is found to be promoted by also passing atmospheric air through the liquid.

Heat from any outside source may, if de sired, be applied during any of the stages constituting this improved process. It is assumed that the well known cyanid process for the extraction of gold from its ores may be represented by the following equation:

According to the present invention thefollowing are the probable chemical reactions which take place, methane and aluminium carbid being taken as examples of a hydrocarbon gas and a metallic carbid, respectively:

I. When methane is passed through a cyanid solution containing goldzmuqon +20H,+H,0=Au,o+2c11,+2KoN+2HoN= As explained in the specification of our application Serial No. 700,107, the precipitation of the metallic gold is more rapid in an acid than in an alkaline solution,

II. When aluminium carbid is added to a cyanid solution containing gold, the equation is as follows:

On the addition of aluminium carbid to the solution of AuK(ON) the nascent CH immediately decomposes the double cyanid'of gold and potassium according to the above equation, and the gold is rapidly precipitated in a metallic state.

Commercial aluminium carbid generally contains free carbon. This separates during the reactions and remains insoluble with the metallic gold.

What we claim is 1. A process for the precipitation of precious metals from their aqueous cyanid solutions, consisting in treating such solutions with a hydrocarbon gas produced when a metallic car-bid is decomposed by water and capable of precipitating the metals in a metallic state.

2. In a process for the precipitation of precious metals from their aqueous cyanid solutions, by treatiu g such solutions with a hydrotreating such solutions with methane, the addition of aluminium carbid to the solution to produce the methane in a nascent condition.

In testimony whereof we have hereto set our hands in the presence of the two subscribing witnesses.

FREDERICK WILLIAM MARTINO. FREDERIO STUBBS.

WVitnesses:

J OSEPI-I BRIGHT, THoMAs HARVEY. 

